The photoprotein aequorin emits light by an intramolecular reaction when Ca2+ is added under either aerobic or anaerobic conditions. Previously reported evidence has indicated two possibilities: (i) the functional group of aequorin is coelenterazine itself, a compond that plays key roles in the bioluminescence of various other types of organisms, or (ii) it is the enolized form of this compound...

The luminescent protein aequorin from the jellyfish Aequoria victoria emits light by an intramolecular reaction in the presence of a trace amount of Ca(2+). In order to understand the mechanism of the reaction, a study of structure-function relationships was undertaken with respect to modifying certain of its amino acid residues. This was done by carrying out oligonucleotide-directed site-speci...

The effect of the phorbol esters phorbol 12-myristate 13-acetate (TPA) and phorbol 12,13-dibutyrate (PDB) on changes in free Ca2+ concentration ([Ca2+]i) in single rat hepatocytes, microinjected with the photoprotein aequorin, were investigated. [Arg8]vasopressin and phenylephrine induced a series of repetitive [Ca2+]i transients. Phorbol esters inhibited the alpha 1-adrenoceptor-induced respon...

Single rat hepatocytes microinjected with the photoprotein aequorin were stimulated with glycogenolytic agonists or low concentrations of fluoroaluminate. Both protocols resulted in the generation of oscillations in cytosolic free Ca2+ levels from a resting value of approx. 200 nM and peaking at over 600 nM. However, oscillations induced by receptor-dependent agonists were more regular in both ...

local Ca2 changes and effects on cell function has been Robert Marsault, Marta Murgia, very difficult to obtain. In fact, while the Ca2 dependence Tullio Pozzan and Rosario Rizzuto1 of various processes occurring at the cell surface has been Department of Biomedical Sciences and CNR, Center for the Study of investigated thoroughly in a large number of cell models, Biomembranes, University of Pa...